Basement waterproofing for a new build in Cornwall

Client: Bude Construction Ltd

Products Used: Koster Repair Mortar Plus


Shop is just one of the few hamlets that make up the area of Morwenstow in Cornwall. Morwenstow also features the National Trust owned Coombe Valley and tucked away beaches such as Duckpool, Stanbury Mouth and Marsland Mouth, all facing part of the Atlantic Ocean.

The client was looking for a waterproofing system for their new build home as part of the construction was fully below ground.  At the time of the survey, the main structure of the property was built, and the ground, which is mostly made of clay type soil, was excavated at the rear. The client’s instructions were to provide an external Type A waterproofing system to the rear section of the property, which was to be below ground. Timberwise understood that the Insulating Concrete Form (ICF) was to be filled with a waterproof concrete (in a single pour with no day joints) which would give the project two forms of waterproofing – Type A and Type B.

Insulating Concrete Formwork (ICF) is an energy-efficient building method that creates, in this instance, insulated structural walls for residential buildings — made up of a series of lightweight polystyrene forms that easily fits together on site, which is then filled with an insulated concrete formwork (ICF). The benefits of using such a method are that the structure offers excellent insulation and airtightness performance, whilst overall costs compete with more mainstream walling systems.

Did you know?

Historically the area was of great importance as it was used a harbour, and then a source of sea sand useful for improving the moorland soil. Within the Victorian era, it was a popular seaside destination.


Timberwise Technicians applied Koster Repair Mortar Plus to the waterproof fillet at the wall/slab joint to protect from movement and cracking. This repair mortar is a watertight and fast setting repair mortar used in this instance for watertight repairs and touch-ups.

The Technicians then installed Type A RIW Sheetseal 226 membrane vertically down the external face of the ICF, lapping it over the toe at the base. A final sheet of the membrane was applied and then bonded and sealed as well as a RIW Double Drain geotextile drainage and protection layer over the top of the sheet seal.

As the customer did not live near a flood risk area, there was no need to design a waterproofing system for mass surges of water such as burst riverbanks or unprecedented rainfall.  Flood protection systems incorporate barriers and the like to stop water entering the property through doorways, air bricks and drainage, this waterproofing system was designed to protect against water entering the property through below-ground walls and floors.

Timberwise has over 50 years of experience in providing exterior and interior below ground waterproofing designs to ensure a dry environment, so the customer could feel rest assured they were in safe hands with Timberwise. The waterproof design was in line with guidance from the British Standard, BS8102:2009 code of practice for protection of below ground structures against water from the ground and Timberwise’s waterproofing specialists held the industry’s CSSW waterproofing qualification. Along with our design and installation service, our waterproofing solutions include long term insurance backed guarantees and servicing agreements ensuring complete peace of mind.


The home is set to complete in early 2020 and once built would make an idyllic family home.

Speak to a Waterproofing Design Specialist in Cornwall

All our basement solutions also benefit from our design and installation services along with our long-term insurance backed guarantees. This ensures you have complete peace of mind that your basement will remain dry for the years to come.

You can trust Timberwise to provide you with the right basement waterproofing systems for your new home. Don’t hesitate to contact Timberwise and request a survey online. A survey through Timberwise will allow our waterproofing team to be able to identify the full extent of your project.